This page of A Plague Tale Innocence has a walkthrough for chapter 9 - In the Shadow of Ramparts. Amicia is without Hugo. The girl must find Sanguinis Itinera - a book that can help the boy. Read the walkthrough to, e.g. learn how to reach the university unnoticed, or how to enter the university.
Searching for the university
Follow Melie. She will lead you to the city's entrance. After that, your paths will diverge. You reach a tower - climb the stairs. You will only encounter two guards. If you stay away from them, they won't notice you. Eventually, you will reach the top of the stairs.
The road to the University
You reach the top of the tower. Jump off it and move on down the stairs. Soon, you will encounter two guards. You can eliminate them, however, if you wait, they will eventually leave and you will be free to go.
Move further - you will see two guards. Instead of going in their direction, head to the right. You will encounter another guard. Kill him to distract the rats. Light the lantern to pass freely. Use a stick (you can also pass without it - this depends on where you killed the enemy).
Turn left and jump over the barricade. Keep moving forward. You will come across another two guards. You have to eliminate them. As for the one located a little closer, you can simply use a stone to break the lantern. Use Devorantis on the second guard.
Move to the stairs. Get on the stairs and then jump on the platform. From there, you will be able to reach the roof. Follow it until you reach the ladder. Get down and then approach the gate. There, you will find a door through which you can pass.
The building is filled with rats. Use a slingshot to shoot down the corpse hanging from the ceiling. An enemy will come here to check the noise - shoot his lantern. This way, you will be able to pass safely.
Leave the building - you will find gallows. You have to go under it to move further. You have to get rid of the rats. You can do this by knocking the corpse or by using Luminosa.
You reach a small yard with a guard. Shoot down another corpse from the gallows and set the torch on fire. You can also eliminate the guard who is patrolling the area. However, this is not mandatory. Move out from the cover and jump on the platform . There, you will find a stick. Use the nearby lantern to set it on fire. This will allow you to move under the second part of the gallows .
Once you get out, you will encounter a guard blocking the path you have to follow. You can kill him or grab a nearby vessel to distract him.
Follow the path - you will reach the cemetery gate. You have to go through it to reach the university. Unfortunately, the entrance is closed. Go to the right. You will find a rotating lamp. Use it to get to the open door. Inside, place the map twice to clear the path. Thanks to this, you will enter the cemetery. You also learn Odoris recipe - this potion lures rats.
Use it to move further. Drop it to clear the path. At some point, you will reach a great crevasse. You can't get out of it. To do that, you will need an extra platform.
Move the lamp inside the crevasse to illuminate the path leading up. Follow it. A cart is standing on the right, behind the fence. However, it is surrounded by rats.
Move the nearby lamps so that one of them will illuminate the area behind the fence. Use Luminosa to destroy the objects behind the fence.
You can now take the chest and put it in the crevasse.
You can continue moving through the city. Follow the linear corridor - you will encounter an enemy with a shield. You have to use him to distract the rats. Hit the armor container with a rock. Throw Odoris at him as soon as the enemy drops the light source. It will attract rats.
Moving on, you will encounter two enemies. The safest way to deal with them is to eliminate these enemies. Remember that one of them wears a helmet - you have to use Devorantis.
Move on. You will come across a large group of rats blocking the passage. Use light to scatter some of them. As for the rest, use either Odoris or Luminosa to get rid of them.
Entering the university
Follow this path - you will reach the university's yard. Shoot down the cage with rats and kill the two guards that stand in your path to the stairs (remember, they have helmets).
At the top of the stairs, wait until the patrol to your right passes you. Go to the alley on the same side. There, you will find an entrance.